Antibody Structure

Antibodies also known as immunoglobulins are key players in the humoral immune response against foreign antigens.

They are proteins that consist of four polypeptides in a Y-shape structure. With two identical heavy and two identical light chains. Linked together through a combination of noncovalent bonds and covalent disulfide bonds.

At the very tips of each polypeptide chain are unique variable domains that selectively bind antigens. While some parts of this region interact directly, other parts provide structural support for these binding sites.

In contrast, the stem region of the antibody, known as the constant region, determines the specific immunological mechanism of action depending on the class.

For instance, one type, Immunoglobulin E, is secreted in the body in response to an allergen, like cat dander, and mediates the allergic reaction.